The purpose of such an optoelectronic sensor device is to detect the quantity of moisture precipitating per unit of time on the front or rear windshield of a motor vehicle. This information is used to automatically control a windshield wiper system associated with the transparent pane.
A device for controlling a motor-driven windshield wiper system is disclosed in German Patent No. DE 33 14 770 Cl, in which a waveguide element is attached to the inner surface of a transparent pane to guide a beam emitted from an associated beam transmitter. The beam is coupled into the transparent pane, and after at least one reflection at the outer surface of the pane, is decoupled from the waveguide element and directed to an associated beam receiver. The waveguide element, the beam transmitter, and the beam receiver are disposed within a protective housing to assure an accurate measurement.
This type of waveguide element, including at least one beam transmitter and at least one beam receiver disposed within a housing, is disclosed in German Patent No. DE 40 06 174 Cl. The housing described in that patent has clip means including latching arms with associated latching cams (barbs) disposed at the base part of the housing which engage latching recesses of the waveguide element to secure the housing thereto. Due to the considerable mass of the components connected to the waveguide element by way of the clip means, and the relatively large forces occurring in a motor vehicle as a result of, for example, acceleration, the housing components may loosen such that they disengage the waveguide element.